import hashlib as hasher;

import datetime as date;


class Block(object):
    def __init__(self, index, timestamp, data, previous_hash):
        self.index = index;
        self.timestamp = timestamp;
        self.data = data;
        self.previous_hash = previous_hash;
        self.hash = self.hash_block();
        pass;

    def hash_block(self):
        sha = hasher.sha256();
        sha.update(str(self.index).encode('utf-8') +
                   str(self.timestamp).encode('utf-8') +
                   str(self.data).encode('utf-8') +
                   str(self.previous_hash).encode('utf-8'))
        return sha.hexdigest();


def next_block(last_block):
    this_index = last_block.index + 1;
    this_timestamp = date.datetime.now();
    this_data = "Hey! I'm block " + str(this_index);
    this_hash = last_block.hash;
    return Block(this_index, this_timestamp, this_data, this_hash);


def create_genesis_block():
    return Block(0, date.datetime.now(), "Genesis Block", "0")


# Create the blockchain and add the genesis block
blockchain = [create_genesis_block()]
previous_block = blockchain[0]

# How many blocks should we add to the chain
# after the genesis block
num_of_blocks_to_add = 20

# Add blocks to the chain
for i in range(0, num_of_blocks_to_add):
    block_to_add = next_block(previous_block)
    blockchain.append(block_to_add)
    previous_block = block_to_add
    # Tell everyone about it!
    print("Block #{} has been added to the blockchain!".format(block_to_add.index))

    print("Hash: {}\n".format(block_to_add.hash))
